A Life For a Life
by mapplepie
Summary: TRF. John can't accept the fact that Moriarty is alive while Sherlock is dead, and he's willing to correct the wrong. It's not revenge. It's much, much more than that. "Do you believe in 'a life for a life?" Necromancer!John


_A/N: Sometimes I wonder to myself why Necromancer!John isn't a thing yet, and then I realise I'm the only weirdo who likes it enough to write it... What can I say?_

* * *

In the days after Sherlock's death, John's life grew progressively greyer. Sherlock had been John's life; if it hadn't been for the consulting detective, John would've lived out the rest of the years after Afghanistan as nothing more than a hollow shell of himself. It was Sherlock who introduced him to adventures the common Londoner could only imagine. It was Sherlock who provided adrenaline pumping excitement that took away his psychosomatic limp.

But now Sherlock was gone and everything was back - his limp, his survivor's guilt, his feelings of helplessness, uselessness. Everything.

John hated it.

And just when the sombre days seemed like it couldn't get any worse, it did.

Mycroft's appearance at the flat was unexpected, unwelcomed, and the bearer of unpleasant news once more.

"What do you want?" John snapped, the moment he hobbled to the door, wrenched it open, and found the elder Holmes' aristocratic mug staring impassively back at him.

Mycroft was unmoved by his tone. He waited a polite second for John to invite him in, before sidestepping the doctor when John only stared blandly back.

Mycroft moved towards the living room and lowered himself onto Sherlock's sofa. There was a long pause as the older man observed John, as if deducing his possible reactions, before he broke the silence between them, launching straight to the point.

"Moriarty," Mycroft said, enunciating each syllable slowly and clearly, "is in our custody."

John froze at the words. The world tilted for a whole of a second before he finally managed a quiet " _What?_ " in a loaded whisper that entirely summed up the roaring maelstrom in his head.

"Moriarty is in our custody," Mycroft repeated.

John shook his head. "No," he said sharply. "No," because he'd heard the truth of Sherlock's jump from Mycroft himself months ago. John had stormed the Diogenes Club when he could no longer stand the guilt, the confusion, the hurt of Sherlock's death. He'd threatened and demanded _everything_ from Mycroft, consequences be damned, and Mycroft had complied. There, John was told of Moriarty's plot – the hired gunmen targeting Sherlock's friends, the fall of Sherlock as a signal to retreat, and the suicide of Moriarty to seal any alternative paths. "You told me…"

Mycroft tipped his head.

A growl ripped out from within John's throat. " _You lied to me!"_

Mycroft was unflappable as always. "Lied? No, Dr. Watson," the man replied, shaking his head. "Withheld information, perhaps."

"You told me Moriarty died," John hissed.

There was something vaguely apologetic in Mycroft's expression – the way he gripped the ribbed Whangee handle of his umbrella, and the small crease between his brows – but John didn't care.

"Indeed. It was believed so," the man began smoothly in that imperturbable voice John was starting to hate more and more, "However we received intel in the later weeks that disputed that fact. Perhaps Moriarty _had_ been up on the rooftop, but the body recovered by my men had merely been a cleverly chosen imposture."

But that had been _months_ ago, and this was the first time John was hearing about it. The doctor's eyes narrowed at the admission, teeth tightly clenched. "And you failed to inform me," he stated dryly.

"There was no reason to do so."

 _"The hell there wasn't!"_ John rose from his chair, eyes ablaze. "Sherlock was my best friend, he -" But Mycroft didn't react to his outburst, looking so used to it – and he probably was, because when Sherlock was alive he did anything and everything just to get a rise out of his brother. John was supposed to be the mature one of the former duo. Swallowing down his anger, John took in deep breaths. "Okay," John finally said in a tightly controlled calm, teeth still clenched and grinding together, "And now that you've found him, the real him, what do you plan to do?"

"He will be put on trial for his crimes."

John scoffed. "And likely get off scot-free," he argued. The last time Moriarty sat on trial, even with video evidence of his crimes, he'd gotten away. He'd turned the crime onto Sherlock. He played everyone for fools. "The man has everyone under his thumb."

Mycroft's eyes darkened at the reminder. "I assure you Dr. Watson, I will not allow that to occur once more." Not under his watch, the man's posture seemed to promise. "He will be found guilty and imprisoned for life for his crimes."

John's eyes slid shut, as if holding himself back from bursting out. Then, his voice, sounding so dangerously silky, murmured: "And if I suggest an alternative?"

Mycroft inclined his head.

The smile John shot at him was full of teeth, stretched on a face lacking humour. The thing was, John had been rolling a certain thought over and over his head for the past month now. The world needed a Sherlock. When it came down to it, John would've gladly, gladly given up his own life if it meant getting Sherlock back, but now, knowing that Moriarty was alive changed _everything_.

John ignored the way the elder Holmes' eyes bore on him, scrutinising his every action. "Do you believe in a life for a life?" John asked instead, in a hushed voice, eyes glistening in something mysteriously unreadable and chillingly dark.

Mycroft's eyes met his own, and John could tell the man didn't know what to make of his words. For once, Mycroft was sorely lacking information, and everything he _could_ infer was unlike the good doctor. "Revenge is not the key," Mycroft responded crisply, pulling out his best deduction with the scant facts he was given. And Mycroft highly doubted his brother would approve of it if he allowed John to do so either.

John, though, only shook his head. "No. It's not revenge," the doctor replied tightly, still in that peculiar manner. "It's much, much more than that."

The doctor finally moved across the room, sitting down on the client couch, eyes never leaving Mycroft. He discarded his cane aside.

"Doctor-" Mycroft began.

"Let me see Moriarty," John interjected, a stubborn tone ringing through his words. "Let me talk to him."

"You should not put yourself through this."

"You don't know what I'm putting myself through," John snapped. "He shouldn't have messed with my friends in the first place."

"And you wish to see him alone?" Mycroft gathered, his voice telling of what he thought about that dangerous idea. No matter how chained down the consulting criminal was, his words were also a tool. His words, his posture, his malevolent smirks, and the way he never cowed no matter his circumstances made one fear and wonder and watch their backs in paranoia every night.

"You don't trust me alone with him?" John stated. There was unexpected amusement in his tone. "Then I'll go with Sherlock," he said, much too casually.

The implication struck Mycroft in a second. It was an incredulous request. "You wish to have my brother's body present."

"Yes."

"Dug up from where he rests in his grave."

John looked continuously undaunted. "I asked for nothing when Sherlock's body was buried," John said softly, hands clasped in his lap. "I accepted it. You know how little he valued your opinion but I let you arrange it all for your peace of mind. This is the only thing I ask for."

A normal man would have immediately questioned the John's sanity. Mycroft was never normal; he was cut from the same cloth as his brother, after all. "It has been months since Sherlock has been buried. He is not in the best conditions," he said, sounding as though he was considering the request.

"I know."

Mycroft gave a thoughtful hum. "What do you plan with him, doctor? Shock factor? Moriarty will not be intimidated by such acts."

"I know."

"And if I allow you that, do I have your word you will not to seek revenge on Moriarty?" Mycroft continued, and really, that was the most important question to be answered. His brother would never rest in peace if he knew Mycroft allowed his precious flatmate (friend) to break the law for his sake.

There was a pause before John finally replied, slowly and controlled, and too worryingly like he was choosing his words carefully. Yet, there was nothing Mycroft could pick out as a technicality John could squirm around. "A dead body will enter the room, and a dead body will exit. I won't add an extra count to it."

Mycroft closed his eyes. "I will think on it," he finally murmured. He headed towards the door when it was clear there was nothing left to discuss. "If that is all, good day, Dr. Watson," Mycroft bid.

John's eyes burned unnervingly on his back as he descended the stairs, stirring paranoia. Mycroft wished he knew why there were cold shivers running down his spine, despite John's promise.

Unless, of course, John was planning to go back on his word. But even if he did, Mycroft didn't think he had the heart to stop the good doctor.

God knows how long he had contemplated ending Moriarty himself.

* * *

Jim Moriarty grinned in his chair.

Jim's every limbs were handcuffed to a metal chair, which was in turn bolted down in the middle of a warehouse out in the middle of nowhere. John was vaguely reminded of his first meeting with Mycroft, except sitting was mandatory for the opposite party, and he was the one in control this time. There was an echoing drip of a leaky pipe in the background, accentuating how alone the John and Jim were in that isolate warehouse.

The consulting criminal looked forever pleased, despite his grim situation. "Ah, Johnny boy. Did big brother decide to give you a go at me as well?"

Mycroft's men had suggested a gag, but John had refused, citing his desire to speak with Moriarty. John was quickly regretting that decision. "Are the handcuffs your touch?" the man continued with a croon, squirming lewdly in spot, "How _kinky_."

"Shut up."

Jim's eyes strayed off to the side of the warehouse where a dirt saddled coffin sat. His eyes widened in surprise before quickly narrowing. "Can't say much for your interior designing."

"I said shut up."

"Hmm," Jim hummed, never one to take orders; not from someone like John. Still, his wandering eye betrayed his lack of care, zeroing in on the coffin every so often. For all his brains, even Jim couldn't tell what John was up to with it. "Are you planning to tell me why I'm here, or just stare at my lovely face all day long?"

John leaned forwards, eyes narrowed. "For Sherlock," he said succinctly, but it wasn't like Moriarty expected John to wax poems at him.

Jim gave a bark of laughter, the loudness bouncing off walls and echoing through the abandoned warehouse until it warped into something disturbing.

"Precious Sherly is d _ea_ d," he sung.

"Because you killed him!" John snapped, unable to help himself. Jim's words were suffocating, pitched to resonate hauntingly from all around. "Sherlock was a good man. It should have been you."

"Are you going to kill me now, dear doctor? What would Sherlock say?" the criminal whimpered lowly with a pitiful sound from the depths of his throat. Then, abruptly his face stretched into a grin full of teeth. "Oh wait, he's _dead_!"

The staccato laughter filled up the warehouse.

John exhaled hashly. "The only dead man in here is you," he hissed.

"The body in the coffin begs to differ!"

Enough was enough.

John turned away from Moriarty, setting to work, refusing to give the criminal the satisfaction of a response. He kneeled by the lone coffin and cracked the lid open. Immediately, the pungent smell of decaying flesh spewed into the air.

Jim visibly choked, but managed a " _Eww_ ," that didn't sound as horrified as he actually felt.

John disregarded it. He reached down into the open coffin, arms scooping out the dead man without any regards to the state of the body.

Jim tugged on his chains when John turned towards him. "Don't put him by me!"

But John did so anyways. He placed Sherlock's body by the foot of Moriarty's chair.

Then, from the back of his pocket, John pulled out a curved knife. It was an eerie looking thing with a short ebony handle and a yellowing blade engraved with unreadable symbols. In an unhesitant movement, John pulled the knife over his own hand, watching the blood drip down.

Sherlock's unmoving body caught every single drip.

"What are you doing now, Johnny boy?" Jim demanded, the question burning on his tongue in his desire to know.

John regarded him with strangely curled lip of a smile. "You tell me," he said, walking casually over.

Chains rattled.

John slowly lifted the knife, running it once over Jim's wrists. Red bloomed underneath. John caught the flow with a cupped hand.

"Torture is unbecoming of you," Jim stated, his voice crooning as usual, but John didn't need to be a Holmes to catch the hitching breath and flickering eyes.

John swirled the collected blood with his fingers, dipping and dragging it over Moriarty's exposed skin like morbid substitutions for finger paints and canvas.

Jim shivered despite the blood's warmth.

Still, though restraint and hurt, Jim refused to be cowed. He rambled on - the only thing he could do in his state of constraint."If it's all the same, I'll stick with my own cosmetics. Red is so not my colour."

John ignored him.

He moved back to Sherlock, hands still dyed red. Equally mystic runes, mimicking those on Jim, were drawn onto the dead body as well.

"Oh come on, Johnny boy. Just because you're not artistic doesn't mean you have to be rude."

On his back, John could feel Jim's unblinking stare observing him, trying to make sense of things.

He would never understand, but it was only fair Jim knew what John was doing to him, John supposed. His explanation was brief and to the point. "Sherlock's lifespan is over, but you, you still have years left in you."

There was a spark of vague understanding. "Are you trying to transfer my life into your dear detective?"

John stifled a low chuckle, not surprised Moriarty grasped the situation so quickly, even though it was outside his realm of reality. "You sound skeptical."

"I'm a man of science, doctor, and you are too."

John huffed a silent laugh. Moriarty knew nothing about him. The game had been between Sherlock and the consulting criminal. John had been nothing but a forgettable pawn for Jim, cast aside once he'd been forced to do his bit.

How utterly, utterly wrong he was.

John had intrigued Sherlock for a reason, but Moriarty had been too caught up in the shining light that was Sherlock to look into his shadow and see John lurking underneath.

"It's a shame you won't be alive to witness it, then," John murmured, leaning in to give Moriarty a razor sharp grin. "I should thank you for being alive."

Then, beneath the red painted lines, Jim's skin burnt hot like flames. The blood seeped beneath his flesh, disappearing until all traces were gone, and then just when Jim thought that was the end of that, red glowed from within. The details of the runes burst out brightly. He could feel them taking a life of its own, squirming and moving under his skin.

"W-what's going on?"

"Can't you tell?" John asked condescendingly, because wasn't this the consulting criminal who claimed to know everything in Sherlock's life? The arrogance finally slipped off Jim's face completely. John happily enlightened him. " _Necromancy_."

Before their very eyes, the lit symbols intertwined and slithered out from their confines, pooling under Jim. It circled him before latching onto Sherlock's limp body. And when it touched, the ashen detective lit up like a spark, flooding the dim warehouse like a beacon of light.

 _Here! Here!_ Sherlock's body seemed to scream. It was nothing physical, but there was a persistent tug from what Jim could only describe as his _life_ and _soul_ , trying to twist out of his body, enticed by the unnatural _thing_ John had done.

"Stop it!" Jim screamed out, but his voice was much too quiet over the howling behind his ears, and he didn't think anyone heard.

Jim could feel his energy, his life, draining out. Before him, Sherlock's pale, pale skin slowly reverted to the rosy pink tinge of the living. Stitches that held cut skin together melted deep into the flesh until it was near unperceivable behind the returning colour.

" _You_ ," Jim hissed out, staring wide eyed at John, who's glowing eyes were the only indication of his involvement in such a supernatural event.

"You shouldn't have written me off so quickly," John snarled. "And you shouldn't have messed with my friends."

Jim's laboured breaths filled the warehouse, eyes wide and staring incredulously at the supposedly good doctor. Then the situation sunk it – or maybe it hadn't – and he threw his head back and laughed and laughed and laughed a deranged, sobbing laugh that stretched on forever until his weakening organs forced out his very last breath.

Eventually the lingering echoes were the only thing left of Moriarty's legacy, quickly lost into the wind, and John wouldn't have it any other way.

On the floor, Sherlock's body shuddered. John's toothy smirk softened back into a smile at the sight of his flatmate.

Long, dark eyelashes fluttered before they pull back to reveal icy blue eyes. They blinked wordlessly. Sherlock's mouth opened, testing their movements, tasting the dryness, and then he spoke.

His baritone voice was everything John and the whole word had missed from his absent few months. "John?"

"Sherlock," he confirmed.

Then Sherlock's eyes flew wide and wild. Unused muscles strained itself as the consulting detective pushed upwards from the floor. "The gunmen!"

John rushed forwards to help his friend up. "They're gone. Moriarty's gone."

"I- where am I?" The sight of a flustered Sherlock was a rare event, but considering the circumstances, John wasn't surprised.

"A warehouse your brother lent me."

"How- What-" The last of the runes were only fading, and Sherlock's magnificent brain was just waking up from its previously dormant state. Finally, Sherlock took in the situation as quickly as John expected him to. "What happened here?" The detective looked between his empty coffin and Moriarty chained to the chair. A hand pressed against the skin of his own body, before moving towards his heart, then wrist, exerting pressure on the veins. "I- I-"

Sherlock seemed unable to finish the sentence, so John did it for him. "You died."

Sherlock swallowed hard.

John forced a causal shrug, holding tightly in his months of grief. He gave Sherlock's shoulder a tight squeeze. "But now you're alive," he concluded, because that was all that mattered in the end.

Sherlock's expression was incredulous because logic was a stranger in that simple explanation.

"I'll explain later," John promised, giving the detective time to gather his bearings, "But for now…" John reached into his pocket, pulling out the phone that had been buzzing incessantly on his thigh since Moriarty had filled the warehouse with his maniacal laughter. He didn't doubt the men Mycroft situated outside had informed the Holmes about it the moment it started.

"Mycroft," he began, when he finally picked up. The other man interrupted immediately. John sighed. "I'm fine. I'm done, actually," he replied. "No, I think it would be best if you didn't send your men in to pick me up," he answered vaguely. He gave a few more agreeable hums before hanging up and pocketing the phone once more.

"Mycroft is coming," Sherlock stated.

John let out another sigh. "I surely hope so."

Sherlock made a displeased sound from the back of his throat at the talk of his brother, but didn't do anything else. His knowledge and life were months behind, and as much as he hated his brother, Mycroft was also his best source of information – direct and concise, without all the romantics John tended to embellish his tales in.

As the two of them waited for Mycroft's arrival, Sherlock took to inspecting Moriarty's remaining body. The only discernable scar was the long cut John took to his wrist. Otherwise, the consulting criminal looked entirely unharmed with no apparent cause of death.

Sherlock was visibly intrigued.

There was a quiet creak from the far side of the warehouse minutes later.

"Dr. Watson," Mycroft's voice called in, echoing across the distance.

"In here."

The man spoke as he approached, even before he saw the situation. "I warned you against revenge," Mycroft tsked as his footsteps tapped louder and louder.

John supposed between his vague request on the phone and Moriarty's suspicious silence, the man was assuming to worst. But John _had_ promised, hadn't he? _A dead body would enter the room, and a dead body would exit._

"I didn't. I corrected a wrong."

John could hear the frown in the elder Holmes' words. "Is there a difference other than syntax? Wha-" Then Mycroft appeared. There was a clatter as Mycroft's trusted brolly fell involuntarily onto the floor. The man inhaled sharply, arms slack, and feet rooted to the ground. His thought processes stuttered to a halt. "S-Sherlock…?"

"Brother dearest," Sherlock murmur, trying to spit out the word as he'd always done, but his attempt was half-hearted at best.

Mycroft turned his eyes onto the doctor, a faint "What have you done?" whispered on his lips. The man's sight flickered between Sherlock and Moriarty. There was an odd mixture of comprehension and disbelief – because what John had done broke all laws of rationality that the Holmes brothers believed in. "- _How_?"

Sherlock turned eagerly to John. "John," he said simply, but John knew what he wanted. Sherlock's impatient expression was nostalgic and comforting in ways John hadn't known he'd missed until now.

"I'll explain," John agreed. "But first shall we head back to Baker Street? It's a good story," John assured them with a light laugh that carried off the heavy feeling that had been ensnarling him for the last few months. "Perfect for your scientific brains to pick at."

And hopefully John could finish his tale before shock set in for everybody, because John didn't want to deal with that – not before he could make copious cups of tea for everyone. Call him British, but tea fixed everything.

* * *

 _A/n: John's necromantic power is fueled by tea. Actually, if this was a crackfic, that's what the punch-line would be._


End file.
